Number of packets is significantly increased for inbound and outbound calls from .NET 8 to .NET 9

[dlevy-chipotle]

Description

During preliminary testing of a core workload upgrade from .NET 8 to .NET 9, we noticed that our service mesh was running significantly hotter, leading to throttling.

Upon closer investigation, we discovered that the number of packets in .NET 9 is significantly higher than in .NET 8 for the same workload, both for packets received and packets sent. In addition, the packet length in .NET 9 is significantly smaller on average than .NET 8. Finally, we found significantly higher connection counts in .NET 9 over .NET 8.

Configuration

• .NET SDK 9.0.101
• dotnet publish -c Release -o out -r linux-musl-x64 -p:PublishReadyToRun=true
• Alpine Linux containers

Regression?

This appears to be a regression from dotnet sdk 8.0.403 and all previous versions.

Data

Packets Sent/Received

.NET 8

.NET 9

Established Connections and /second

.NET 8

.NET 9

Overall Stats for Client -> Server

.NET 8

.NET 9

Packet Length Comparison

[rzikm]

I think we will need more information about your specific workload. Even better, if you could simplify it to a simple self-contained repro project we could run locally, it would make our investigation a lot easier and faster.

[dlevy-chipotle]

@rzikm makes perfect sense. We'll work on putting together a generic project that demonstrates the issue.

[dlevy-chipotle]

@rzikm please see the attached zip. It's composed of two Ready2Run projects, one targeting .NET 8 and one targeting .NET 9, both set to publish as linux-musl-x64 self-contained projects. There's also a dockerfile for each if you'd prefer.

We did run both sample projects through load tests and they resulted in higher packet counts in the .NET 9 version.

PacketTest_compressed.zip